Radical polymerization kinetics

German, A.L., Ed. Macromol. Symp., Free Radical Polymerization Kinetics and... 

R.A. Hutchinson, M.C. Grady and WJ. Simonsick, Preprints International Symposium on Free Radical Polymerization Kinetics and Mechanism, II Ciocco, Italy (2001). 

Here, gt takes into account one interesting feature of the free radical polymerization kinetics the auto acceleration in the rate of reaction (better known as the Trommsdorff or gel effect). The gel effect is taken into account in the model (42) by including the experimental correlation developed in [18] for the termination rate ... 

As a consequence of the free radical polymerization kinetics, the termination rates are extremely fast in comparison to the slow initiation rates. This results in the formation of high molar mass chains at the initial stage of the polymerization and decreasing molar masses in the latter stages due to the decrease in the monomer concentration. Under these circumstances, broad molar mass distributions are inevitable. 

In contrast to template polycondensation or ring-opening polymerization, template radical polymerization kinetics has been a subject of many papers. Tan and Challa proposed to use the relationship between polymerization rate and concentration of monomer or template as a criterion for distinguishing between Type I and Type II template polymerization. The most popular method is to examine the initial rate or relative rate, Rr, as a function of base mole concentration of the template, [T], at a constant monomer concentration, [M]. For Type I, when strong interactions exist between the monomer and the template, Rr vs. [T] shows a maximum at [T] = [M]q. For type II, Rr increases with [T] to the critical concentration of the template c (the concentration in which template macromolecules start to overlap with each other), and then R is stable, c (concentration in mols per volume) depends on the molecular weight of the template. 

M. Buback and A.M. van Herk. Radical Polymerization Kinetics and Mechanism. Wiley-VCH, Weinheim, 2007. 

Free Radical Polymerization Kinetics of Immobilized Chains... 

When the concentracion of active centres does not change during propagation, we speak of stationary polymerization. All previous and the majority of the presently valid analyses of radical polymerization kinetics assume stationary (or, better, pseudo-stationary [20, 21]) states. The conditions under which the stationary state assumption is a valid and useful approximation, can be expressed as follows [22] ... 

Polystyrene and poly(methyl methacrylate) polymerizations are typical of homogeneous bulk chain-growth reactions. The molecular weight distributions of the products made in these reactions are broader than predicted from consideration of classical, homogeneous phase free-radical polymerization kinetics because of autoacceleration (Section 6.13.2) and temperature rises at higher conversions. 

Computational Aspects of Free Radical Polymerization Kinetics with Chain Length Dependent Termination... 

Comprehensive Models. This class of detailed deterministic models for copolymerization are able to describe the MWD and the CCD as functions of the polymerization rate and the relative rate of addition of the monomers to the propagating chain. Simha and Branson (3) published a very extensive and rather complete treatment of the copolymerization reactions under the usual assumptions of free radical polymerization kinetics, namely, ultimate effects SSH, LCA and the absence of gel effect. They did consider, however, the possible variation of the rate constants with respect to composition. Unfortunately, some of their results are stated in such complex formulations that they are difficult to apply directly (10). Stockmeyer (24) simplified the model proposed by Simha and analyzed some limiting cases. More recently, Ray et al (10) completed the work of Simha and Branson by including chain transfer reactions, a correction factor for the gel effect and proposing an algorithm for the numerical calculation of the equations. Such comprehensive models have not been experimentally verified. 

Pierik, B. Masclee, D. Vollmerhaus, R. van Herk, A. German, A. L. In Free Radical Polymerization. Kinetics and Mechanism, Macromolecular Symposia Series, Buback, M., Ed. Wiley-VCH Weinheim, 3rd IUPAC-Sponsored International Symposium on Free Radical Polymerization Kinetics And Mechanism, II Chioccho/Lucca, Italy, June 3—8, 2001. 

Free-radical Polymerization Kinetics. A general scheme for these reactions is the following ... 

Over 200 references describing spontaneous, and chemically initiated styrene polymerization chemistry are reviewed with special emphasis on advances taking place in the past decade. The review is limited to chemistry useful for making amorphous high molecular weight polystyrene in solution polymerization processes. Chemical initiators have been categorized into three basic groups as follws 1) anionic 2) mono-radical and 3) diradical. Analytical techniques used for determination of free radical polymerization kinetics and mechanisms are also discussed. 

As it is known through Ref. [157], within the framework of fractal analysis the polymerization kinetics is described by the general Eq. (79). The combination of the relationships (79) and (125) allows to obtain radical polymerization kinetics description within the framework of synergetics [166] ... 

Veregin, R.P.N., Odell, P.G., Michalak, L.M., and Georges, M.K., 1996, Molecular Weight Distributions in Nitroxide-Mediated Living Free Radical Polymerization Kinetics of the Slow Equilibria between Growing and Dormant Chains, Macromolecides, 29 3346... 

The kinetics of DMDAACh radical polymerization in water solutions has the same quahtative features, as radical polymerization kinetics of other polymers [1]. In particular, this is expressed in sigmoid shape of kinetic curve Q, , which in general case is divided into three sections initial, of autoacceleration and finish polymerization [20]. For the curve the traditional approaches number, considered in detail in works [1, 20], is used. However, the indicated approaches do not take into account the stmcture of the main element of polymers synthesis in solutions — macromolecular coil and, hence, its possible variations in synthesis process. At present the theory of irreversible aggregation, linked closely to fractal... 

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